struct field add mandatory param 'optional'

examples/example1/example1.yml2

@@ -28,9 +28,9 @@ pEpACIDLang {
             }
 
             struct struct1 {
-                field int int1;
+                field required int int1;
-                field size size1 doc="short doc";
+                field required size size1 doc="short doc";
-                field string string1
+                field optional string string1
                     doc="""
                     Multiline
                     Doc

idl/pEpACIDLang.yml2

@@ -82,9 +82,11 @@ decl item @name;
 // ------
 decl struct @name;
 decl field @optional @type @name;
+// @optional valid values are 'optional' and 'required'
 // optional attrib 'doc'
 // optional attrib 'deallocator' (for non-idl types)
 
+
 // Method
 // ------
 decl method @name;

idl/test_api/test_api.yml2

@@ -18,8 +18,8 @@ pEpACIDLang {
             }
 
             struct struct1 {
-                field int int1;
+                field optional int int1;
-                field size size1;
+                field optional size size1;
             }
         }
     }

lm-c99/tests/test_ig_c99/test_ig_c99.yml2

@@ -105,9 +105,9 @@ pEpACIDLang {
             }
 
             struct struct1 {
-                field int int1;
+                field optinal int int1;
-                field size size1;
+                field optional size size1;
-                field string string1;
+                field optional string string1;
             }
 
 
@@ -124,9 +124,9 @@ pEpACIDLang {
             }
 
             struct struct1 {
-                field int int1;
+                field optional int int1;
-                field size size1;
+                field optional size size1;
-                field string string1;
+                field optional string string1;
             }